Liquid level control



July 26 1932. DE FLOREZ LIQUID LEVEL CONTROL Filed July 27, 1928 Snow W01 $51 6 1'; awe (MW Patented July 26, 1932 Luis m: nonnz, or roman, comc'rrcur LIQUID LEVEL CONTROL Application filed July 27, 1988. Serial No. 885,374.

nary control devices do not function prop-v erly if placed therein. My invention is particularly adapted to the control of the liquid level of petroleum hydrocarbons, such as the complex mixtures produced by cracking and which are in equilibrium with a vapor 'phase, as for example in a separator, still or 7 rectifying column. In accordance with my 5 invention a minor part of the vapor phase is continuously condensed and diverted into a receptacle, the liquid level in which receptacle is in hydrostatic equilibrium with the liquid level in the main container so that the level control devices are surrounded by and actuated by the condensate so produced and not by the residua which have accumulated in the principal container. In the case of petroleum hydrocarbons these residua are ar- -ticularly apt to form coky deposits w ich seriously interfere with the operation of any level control device placed therein, and this difliculty is entirely eliminated by my invention. The invention will be understood from the following description read in conjunction with the drawing; in which Fig. 1 is an elevation with parts in section of a preferred embodiment of myinvention; v

Fig. 2 is a top view of a part of Fig. 1 showing an auxiliary form o pumping apparatus;

Fig. 3 is a vertical section through a form of valve control apparatus shown in Fig. 1;

Fig. 4 is a horizontal section through part of Fig. 1 on the plane denoted by the line 1-1; and

Fi 5 is an outside view of a part of Fig. 1.

Re erring to Fi 1, the numeral 1 denotes a container in which a liquid is fractioned,

such as a separator or rectifying column. This rectifying column has an inlet pi e 2 from which material such as amixture 0 pctroleum hydrocarbons partly in the vapor phase'may be supplied to the column. The column is equipped with a series of horizontal partitions 3 which, in turn, carry liquid vapor contacting devices, such as bell caps and overflow pi es, not shown. A cooling coil 4 u is preferab y provided in the upper part of the column, and the vapor outlet pipe 5 is adapted to carry the finally rectified vapors away from the column. Any liquid bottoms accumulating in the base of the column may 00 be withdrawn through the pi e 6 which is connected to the suction side 0 the oil pump The pumped oil ma be discharged throughthe pipe 8 leading rom the discharge side of the pump to an accumulator. A side inlet 9 is tapped off from the column at a point above the liquid level and preferably adjacent the upper part of the column 1. This pipe may be left uncovered to provide a certain amount of condensation but is pref- 7o erably surrounded in part by a condenser, such as 10, equipped to receive cooling liquid by means of the inlet and outlet pipes 11 and 12, respectively. The pipe 9 discharges into a receptacle 13 which is positioned so as to include the upper and lower limits, respectively, of the level to be controlled in the column 1. The receptacle 13 is connected back into the column. at a point below the liquid level by the pipe 14, so that the levels within the receptacle 13 and column 1 will always be in substantial hydrostatic equilibrium. A float 15 is provided in the receptacle 13 Fig. 4 which is rigidly connected to the shaft 16 which, in turn, extends through the stufiing box 17 on the side of the receptacle 13. This shaft is connected directly to the plug 19 in the cock 18, so that the upward movement of the float will operate to open the cock 18 and the converse downward movement of the float will 0 operate to close it. 18 is located in the pipe 20 and is therefore. adapted to throttle and control the flow of liquid through the said pipe. The receptacle 21 in the said pipe provides a reservoir of liquid, the level of which may be observed by means of the sight gauge 22. The pipe 20 is connected to the suction side of a small auxiliary pump 23 which is bolted to, or otherwise rigidly secured to, the steam end 24 of the. pump 7. This pump is of ly so as to carry the yoke 27 the carrier the conventional piston type operated by the shaft which enters the pump through the standin box 26. The'piston rod carries the yoke 2 Fig. 2, which, in turn, is actuated by 28 which is ordinarily a rod atextremity carr1es a pin 34. This pin engages a slot in the weighted handle of the cock 36 which controls the flow in the pipe 37 carrying steam to the steam endof the pump A cover plate 38 is provided, on the piston chamber so that the piston 32 will never be completel expelled from the piston chamber 31. e pipe 20 leads from the piston chamber 31 back to thecock 18, thereby perv pumped a continuous circulation of the liquid from the reservoir 21 through the pump 23, piston chamber 31 and back to the reservoir 21 subject to the throttle control of the float 15 operating through the cook 18.

In 0 eration material to be rectified, such mitting V as crac ed material withdrawn from the ditoms, base of the column and flows do ill the hose of several horizontal level existing in the column 1.

gesting column of a cracking unit operating on petroleum oil, isintroduced to thecolumn 1 throu h the pipe 2. Cooling medium is supplie through the coil t to control the degree of rectification taking place in the rectifying column and thereby produce a accuses stron tendency to form. a deposit which woul seriously interfere with the operation of any liquid evel device in position in the column.

the pressure in the iston chamber 31. This automatically permits the iston 32, the piston rod 33 and pin 34 to fall, thereby operating to open the cock 36in the steam lme 37 and either starting the pum 7 or causing it to operate more rapidly. he operation of the pump 7 carries in operation the pum 23, thereby pumping a continuous supply 0 liquid from the reservoir 21. Whenever the liquid level in the column 1 has fallen to a predetermined point the float 15wil1 0 rate con= versely to close the cock 18, there y causing an accumulation of pressure in the piston chamber 31 which operates conversely to close, or partly close, the valve 36 thereby cutting down the steam and slowing down the pump until the predetermined level in the column is again attained. In practice very little hunting is observed. The adjustment of the pump s eed by my device will ordinarily be such t at very little variation in liquid level in the column is experienced, and the column opcrates continuously at substantially the predetermined and desired liquid level therein.

It will be apparent from the foregoing that my liquid level control device is free from the diiliculties which have characterized previous control devices positioned within the column itself and is susceptible of continuous and et= ticient operation regardless of the refractory character of the livid bottoms in the main container, the love of which is to he con= desired composition of overhead vapor which trolled. is diverted away through the pipe 5. lBotlt will of course he understood that the loreor heavy residuum, accumulates in the l, while liquid and vapor equilibrium exist above the partitions 3 becoming propoint Part phases in partial gressively lighter and lower in bOlllli as the top of the column is approach: of the material in the upper p of I the column, prefer the vapor, is divcned continuouslyth the pipe 9 and, iii not al ready liquid densed in the condenserll) nvvardly into the receptacle 13, thereby maintaining in the recep level oil liquid substantially identical with the lt will he noted, however, the composition of the liquid in the sole l3'isi it off the material adjacent i' oil the column l, which p id relatively stable not c form carbon-a stop cont I contrary i posits and gum up or in, whereas on the a residue accumulating in columnrnay he of an as phalticor y character and may have a v the level of the liquid to he controlled, a con nection between said receptacle and said con= tainer below the liquid level to he controlled, a primary pump connected to said container below the level to he controlled, an auxiliary pump actuated hy said primary pump, means for supplying liquid to said auxiliary pump,

()1 a discharge circuit from said auxiliary pump,

means responsive to variations in levelin said receptacle adapted to regulate the discharge from said auxiliary pump and thereby vary the pressure in saiddischargecircuit, and

means for controlling the primary pump to v I c arge circuit.

naive to variations in pressure in said 2. A device for controlling the level of liquid accumulatingin a container compris-- ing a liquid discharge outlet from said contamer, a primary. pump connected to said discharge outlet, a receptacle positioned at substantially the level to be controlled, a pipe connecting said receptacle with said container below the level to be controlled, means for abstractingmaterial from the said container at a pomt above the level to be controlled, and for discharging said material in liquid form into the said receptacle, means responsive to the liquid level in said receptacle, an auxiliary pum actuated by said rimary pump, means or supplying liqui to said auxiliary pump, a discharge circuit from said auxiliary pump, means for causing the said means responsive to variations in liquid level to regulate the discharge from said pump and thereby vary the pressure in the said discharge circuit, and means controlling the said primary pump res nsive to variations in pressure in said disc arge circuit.

3. A device for controlling the level of liquid accumulating in a container comprising a discharge outlet from said container, a primary pump connected to said discharge outlet, a receptacle positioned at substantially the level to be controlled, a pipe connect-' ing said receptacle with said container below the level to be controlled, means for abstractin material from the said container at a pomt above the level to be controlled and for discharging the material abstracted in liquid forminto the said receptacle, a float in saidv receptacle, an auxiliary pump actuated by said primary pum means for supplying liquid to said auxi iary pump, a discharge circuit leading from said auxiliary pump connected to said receptacle, a flow control receptacle operate to regulate the discharge a responsive to variations in pressure in said said circulating system, and means responslve to said pressure variations for regulatdevice, means for causlng movement of said float to vary the adjustment of a flow control device whereby variations in level in said from said discharge circuit outlet and thereby'vary the pressure in said discharge circuit, means for controlling the said primary pump discharge circuit.

4. In combinationwith a column for fractionating a liquid having relatively high and low boilmg components, a device for controlling the level of a relatively high boiling liquid accumulating in said column comprising a receptacle, a pipe connecting the re ceptacle with said column at a point below the level to be controlled, means for causing relatively low boiling material withdrawn from the upper part of said column tobe discharged into the said receptacle in liquid form, whereby circulation is established and said receptacle will in operation contain substantially exclusively relatively low boiling material withdrawn from the upper part of said column, and means responsive to the liquid level in said receptacle for controlling the liguid level in said column.

5. n combination with a column for fractionatin a liquid having relatively high and low boi ing components, a device for controlling the level of a relatively high boilingliquid accumulating in said column com rising a receptacle, a ipe connectin sai receptacle with said co umn at a intfiielow the level of the relativel high nents to be controlled? a pipe connectin the rlelceptacle with said column at a point a V0 t e nected. tothe last-mentioned pipe whereby relatively low boilin products condensed in said condenser are ischarged into said receptacle, a float in said receptacle, and means res onsive to movement of said float for contro ling the liquid level in said column.

6. In a fractionating system in combination, a fractionating column, means 9r introducing a fluid mixture to said column, said fluid mixture having both high and low boil-' ing components, means for withdrawing overhead fractions from saidcolumn, means for withdrawing liquid residue from the bottom of said column comprising a discharge pipe and a primary pump connecting therewith. and means for controlling the liquid residue level in said column comprising a receptacle'positioned adjacent the lower section of said column, a pipe connecting said receptacle with said column at a point below the liquid level therein, means for withdrawing fluid from said column at a point above the liquid level therein and for discharging said fluid to said receptacle in liquid condition whereby the liquid in said receptacle comprises only low boiling components of the original fluid mixture introduced into said column, an auxiliary fluid circulating system communicating with both said receptacle and with said rimary pump, means for introducing fluid into said circulatin system, means 'for causing circulation of sand fluid in said circulating system, means responsive to the variations in the liquid level in said rece tacle for causing pressure variations in said primary pump. 1

In a fractionating system in combination, a fraction'ating column, means for introducing a fluid mixture to said column, said evel to be controlled, a condenser con-- iling compofluid mixture having both high and low boiling point components, means for withdrawing overhead fractions from said column, means for withdrawing liquid residue from the bottom of said column comprising adischarge pipe and a primary pump connecting therewith, and means for maintaining said liquid residue in said column at a desired level comprising a receptacle positioned subing to cause the circulation of the stentialiy at tire liquid residue level to lie maintained, a pipe connectinfl said receptacle with said column at a oint low the li uid level 'therein 'means or withdrawing uid from said column at a point above the said desired liquid residue level and for discharg ing said withdrawn fluid to said receptacle in liquid condition, an auxiliary fluid circulating system, means for introducing fluid thereto an auxiliary pump in said circulating system and operatuid m said circulating system, means communicating actuated Toy said primary pump with said circulating system and responsive to variations in the liquid level in said rece tacle for causing pressure variations in.

said circulating system, and means communicating with said primary pump and responsive to said pressure variations for controiling the operation of said primary pump whereb the desired liquid residue level is maintained in said column.

In testimony whereof, l have signed my name to this specification this 24th day of July, 1928.

, LUIS DE amass.

asse ses 

